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Ordovician-Silurian unconformity at Kankakee River State Park, Illinois

Donald G. Mikulic
Donald G. Mikulic
Illinois State Geological Survey
615 E. Peabody Drive, Champaign, Illinois 61820
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Joanne Kluessendorf
Joanne Kluessendorf
Department of Geology, University of Illinois
, Urbana, Illinois 61801
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January 01, 1987


Upper Ordovician and Silurian rocks are well exposed in aseries of natural outcrops along the Kankakee River from Wilmingtonto Kankakee, Illinois. Some of the best exposures occurin Kankakee River State Park, which extends northwest from the town of Altorf for about 6 mi (9.6 km) (Fig. 1). Thre sites are particularly interesting (Fig. 2).

1. Chippewa Campground—a river bluff on the north sideof the river just below the campground (NW¼NE¼SE¼, Sec.36, T.32N., R.10E., Bonfield 7½ minute Quadrangle, WillCounty).

2. Cowan’s Quarry—abandoned stone pits and river bluffson the north side of the river between the river and State Highwa102 (SE½SW½NW½, Sec.26, T.32N., R.10E, Bon field 7½-minute Quadrangle, Will County).

3. Rock Creek—a canyon of a tributary north of the KankakeeRiver, north and south of the bridge on State Highway 102(S¼SE¼SW¼, Sec.32, T.32N., R.11E., Bourbonnais 7½-minuteQuadrangle, Kankakee County).

All localities except Cowan’s Quarry are accessible by passenger car and are a short walk from a highway or parking lot.Cowan’s Quarry is reached by an unmarked and unmaintaineddirt road leading south to the river from Illinois 102 (Fig. 2). This road is generally in poor condition, but is the only place to park as there is no shoulder on the highway. From the dirt road, walkwest about 300 ft (100 m) along the top of the river bluff to theold stone pits.

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DNAG, Centennial Field Guides

North-Central Section of the Geological Society of America

Geological Society of America
ISBN electronic:
Publication date:
January 01, 1987




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